FIELD OF THE INVENTION
This invention relates to a current injection type logical operation circuit arrangement comprising I.sup.2 L elements.
In some applications wherein a logical operation circuit is employed, it is required that a logical value be held when main power supply is interrupted due to accident, failure, erroneous manipulation or the like. In a drive circuit for a switch including a self-restore type contact, for example, when the main power supply is interrupted for one reason or another after the switch has been set to a predetermined logical value having been set prior to the interruption of the main power supply be restored when the main power supply is restored. More specifically, in the case of a switch including a self-restore type contact, the contact thereof is in an open state after the switch has been set; thus, it is necessary to store the set state by means of a drive circuit for the switch. Usually, when the main power supply is interrupted, the logical value should be held by supplying power to all the circuit devices. In the case where the logical operation circuit comprises MOS transistors, due to low current consumption, it has been the practice that power is supplied from an auxiliary current source circuit to all the logical operation circuits. In the case of I.sup.2 L circuit, however, since each element thereof requires an injector current as high as 5.mu.A to 10.mu.A, relatively high current consumption is caused therein; thus, difficulties are encountered in an attempt to supply a current to all the logical operation circuits when each of the logical operation circuits is constituted by a I.sup.2 L circuit. In contrast thereto, when a I.sup.2 L circuit is in a static state, it is possible to hold a logical value by an injector current as low as 0.5 .mu.A. In view of this fact, the inventors have achieved a novel and improved I.sup.2 L circuit device which is so designed that current consumption is minimized by supplying an injector current only to such a portion of the I.sup.2 L circuit as holding circuit or memory circuit.